We report here on the effects of grains of PbS with different length scales on thermal conductivity reduction and bipolar effect ‘suppression’ through macro-properties/microstructure analysis. We found that nanograins can achieve the above goals simultaneously. Combining experimental results and theoretical calculations, we found that the effect of nanograins on the reduction in lattice thermal conductivity can surpass that of nanoprecipitates. Improved properties corresponding to the lowest lattice thermal conductivity in a PbQ (Q=Te, Se, S) system (0.5 W m K−1 at 923 K) and the highest ZT value in PbQ nanocrystalline materials were achieved by the nanograin method.
- Haijun Wu
- Jesús Carrete
- Jiaqing He
